1. Field of the Invention
The present invention relates to an electrostatic capacitive touch sensor.
2. Prior Art
For example, as illustrated in FIG. 25, a conventional electrostatic capacitive touch sensor typically has a construction in which a substrate 90 having fixed electrodes Dx+, Dxxe2x88x92, Dy+ and Dyxe2x88x92 and a dish-shaped metal diaphragm 91 having a conductive property with an operation shaft 91a are formed into an integral part by a rivet 92. In the touch sensor of this type, when the operation shaft 91a is tilted, the metal diaphragm 91 is distorted, with the result that the electrostatic capacitance between the metal diaphragm 91 and the fixed electrodes Dx+, Dxxe2x88x92, Dy+ and Dyxe2x88x92 are allowed to change.
However, the conventional electrostatic capacitive touch sensor described above has the following problems:
Troublesome assembling tasks, such as a joining process (caulking process, etc.) between the metal diaphragm 91 and the operation shaft 91 and a riveting process between the metal diaphragm 91 and the substrate 90 are required, resulting in high costs.
Water, etc. tend to enter the gap between the metal diaphragm 91 and the substrate 90; therefore, an additional sealing member is required so as to make the device water-proof, depending on applications.
Therefore, one object of the present invention is to provide an electrostatic capacitive touch sensor which makes it possible to reduce the number of troublesome assembling processes and to easily make the device water-proof and dust-proof without increasing the number of parts.
Another object of the present invention is to provide an electrostatic capacitive touch sensor which makes it possible to reduce the number of troublesome assembling processes, to easily make the device water-proof and dust-proof without increasing the number of parts, and to provide a high sensitivity as a sensor.
The touch sensor according to the present invention comprises:
a substrate having a group of fixed electrodes formed thereon, and
a movable electrode plate that is integrally molded by using rubber or resin having an elastic property as a whole and has at least a face which opposes the group of fixed electrodes and is made of a conductive rubber or a conductive resin.
In this arrangement, a plurality of variable electrostatic capacitive sections are formed by the group of fixed electrodes and movable electrode plate so that, in response to the magnitude and the direction of a force applied onto the movable electrode plate, the electrostatic capacitances of the respective variable electrostatic capacitive sections are allowed to change.
The touch sensor according to the present invention comprises:
a substrate having a group of fixed electrodes formed thereon, and
a movable electrode plate that is integrally molded by using elastomer as a whole and has at least a face which opposes the group of fixed electrodes and is made of a conductive elastomer.
In this arrangement, a plurality of variable electrostatic capacitive sections are formed by the group of fixed electrodes and the movable electrode plate so that, in response to the magnitude and the direction of a force applied onto the movable electrode plate, the electrostatic capacitances of the respective variable electrostatic capacitive sections are allowed to change.
Furthermore, the touch sensor according to the present invention comprises:
a substrate having a group of fixed electrodes formed thereon,
a movable electrode plate which is formed by using elastomer as a whole and has at least a face which opposes the group of fixed electrodes and is made of a conductive elastomer, and
an operation portion made of a hard material, which is formed integrally with or separately from the movable electrode plate and can transmit force to the movable electrode plate.
In this arrangement, a plurality of variable electrostatic capacitive sections are formed by the group of fixed electrodes and movable electrode plate so that, in response to the magnitude and the direction of a force applied onto the operation portion, the electrostatic capacitances of the respective variable electrostatic capacitive sections are allowed to change.
The present invention, may have a construction in which an operation portion, made of rubber or resin, having a protruding shape, is integrally formed on the movable electrode plate.
In addition an operation portion which is made of elastomer and has a protruding shape, may be integrally formed on the movable electrode plate.
Furthermore, in the present invention, the electrodes of the group of fixed electrodes may be arranged so as to have an interval of 180xc2x0 from each other; thus, based upon a change in the electrostatic capacitances between the two variable electrostatic capacitive sections, it is possible to detect the magnitude in the X-axis direction of a force applied onto the operation portion together with its positive or negative direction.
The electrodes of the group of fixed electrodes may be arranged so as to have an interval of 90xc2x0 with each other; thus, based upon a change in the electrostatic capacitances between the two variable electrostatic capacitive sections that face each other on one straight line, it is possible to detect the magnitude in the X-axis direction of a force applied onto the operation portion together with its positive or negative direction, and based upon a change in the electrostatic capacitances between the two variable electrostatic capacitive sections that face each other on the other straight line, it is possible to detect the magnitude in the Y-axis direction of a force applied onto the operation portion together with its positive or negative direction.
Furthermore, an independent electrode may be formed on a substrate portion surrounded by four electrodes arranged with an interval of 90xc2x0 with each other; thus, based upon a change in the electrostatic capacitance of the variable electrostatic capacitive section that is formed by the independent electrode and the variable electrode plate, it is possible to detect the magnitude in the Z-axis direction of a force applied onto the operation portion together with its positive or negative direction.
In addition, an independent contact-use land may be formed on the substrate portion surrounded by four electrodes arranged with an interval of 90xc2x0 with each other, and a protrusion serving as an electrical contact may be formed on a portion of the movable electrode plate opposing the contact-use land; thus, the switch is constructed by the protrusion and the contact-use land.
Furthermore, in the present invention, a peripheral protruding portion may be formed on the movable electrode plate so as to surround the operation portion; therefore, when the movable electrode plate is attached to a fixing member with the peripheral protruding portion being pressed thereon, it is possible to ensure a sealing property between the fixing member and the movable electrode plate by the elastic restoration force of the peripheral protruding portion.
The substrate and the movable electrode plate may be enclosed by a metal frame, and one portion of the metal frame is bent over so that the movable electrode plate and the substrate are secured to the metal frame in a manner so as to be pressed thereon; thus, it becomes possible to prevent foreign matters from entering the variable electrostatic capacitive section from outside by using a sealing property exerted by the elastic restoration force of the movable electrode plate.
In the present invention, the metal frame has a conductive property so that the movable electrode plate is allowed to hold a predetermined voltage through the metal frame. Furthermore, a protrusion may be formed on at least either one of the opposing faces of the substrate and the movable electrode plate so as to prevent the gap between the group of fixed electrodes and the movable electrode plate from becoming too narrow the operation portion may be provided with a space, and the operation portion may be made of rubber, resin or metal.